# Low Reynolds number flow with thermal convection over an airfoil with simultaneous pitching and plunging motions: aerodynamic coefficients, heat transfer rate and history points data.

## Description

This dataset contains the data of the investigation on the low Reynolds number flow over a NACA0012 airfoil with simultaneous, low amplitude, pitching and plunging motions. In this work, the influence of the buoyancy force (the Rayleigh number) on the flow patterns, the aerodynamic coefficients and the heat transfer rate (the Nusselt number) is studied. Several cases were analyzed with a Reynolds number of Re = 1000, a non-dimensional (reduced) frequency of 7.86, a pitching amplitude of 1° and a non-dimensional (scaled with the chord of the airfoil) plunging amplitude of 0.0125. Three mean geometric angle of attacks were considered (0°, 10°, and 15°), as well as two phase angles between motions (0° and 90°) and Rayleigh numbers ranging from Ra = 0 to Ra = 1 000 000. We found that an increase in the Rayleigh number decreases the aerodynamic performance, and that this effect is reduced by increasing the mean geometric angle of attack. If the mean angle of attack is of 0°, the Nusselt number decreases with an increase of the Rayleigh number; in contrast, if the mean angle of attack is 10° or 15°, the heat transfer rate increases as the Rayleigh number gets higher values. Also, changing the phase angle from 0° to 90° increases the Nusselt number in all cases. A noticeable change in the wake and in the behaviour of the flow velocity behind the airfoil is observed when the Rayleigh number is 500 000 or higher, which may be indicative of a transition in the heat transfer mechanism, changing from a forced convection to a mixed convection. With respect to the files in the dataset, the instantaneous variables (x1 and x2 velocities, pressure and temperature) of the flow at six points in the wake are presented in the folder "hpoints". Each file name is identificated with three parts: the letter "a" is the mean angle of attack, "p" is the phase angle, and "Ra" is the Rayleigh number; the letter "k" means 10^3, and "M" means 10^6. For example, "a00p00_Ra001M.txt" is the file for the case with a 0° mean angle of attack, 0° phase angle and Ra = 1 000 000. In the file, the first line is the number of points, and the following six lines are the coordinates of the points in the flow field. Then, the first column is the time (for a time, there are six rows corresponding to each point), an the following are: velocity in x1, velocity in x2, pressure, and temperature. Furthermore, the instantaneous drag and lift coefficients are presented in the folder "aero_coeffs", and the instantaneous (contour-average) Nusselt numbers are presented in the folder "nusselt". These folders contain sub-folders indicating the phase angle (phi), which also contain sub-folders with the mean angle geometric of attack (0deg, 10deg, and 15deg). Each file name shows the reported quantity (cD (drag coefficient), cL (lift coefficient), or nusselt) and the Rayleigh number (Ra). In the file, the first column is the time and the second is the reported quantity.

## Files

## Steps to reproduce

These results were obtained by performing numerical simulations employing the Nek5000 solver, which uses the high-order spectral-element method to numerically solve the Navier-Stokes equations coupled with the energy equation. Moreover, it uses the Arbitrary Lagrangian-Eulerian algorithm for the mesh motion, which is included to enable the airfoil simultaneous pitching and plunging motions.